INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY ISSN Print: 1560–8530; ISSN Online: 1814–9596 07–344/SAE/2008/10–5–521–525 http://www.fspublishers.org

Full Length Article

Interaction of Aeolothrips intermedius and niger in Controlling Thrips tabaci on Potato

SAYED ALI ASGHAR FATHI1, ALI ASGHARI† AND MOHAMMAD SEDGHI† Department of Plant Protection and †Plant Breeding, University of Mohaghegh Ardabili, Ardabil, Iran 1Corresponding author’s e-mail: [email protected]

ABSTRACT

Aeolothrips intermedius (Bagnall) and Orius niger (Wolff) feed on larvae-I-II and adults of the onion thrips (Thrips tabaci Lind.) in the potato fields of Ardabil region. Predation by O. niger, one female and one nymph-V and A. intermedius, three adults and three larvae-II, was determined in the separated and combined uses at three densities of larvae-II onion thrips with a aim to investigate the additive effect and intraguild predation of O. niger and A. intermedius in the combined uses and compared with the separated uses at three densities of prey. In the separated uses O. niger, one female and one nymph-V, consumed more prey than A. intermedius, three adults and three larvae-II, at three densities of prey. Predation in the combined uses of O. niger and A. intermedius at the 50 and 100 prey densities were higher compared to the separated uses of each predator alone. These results indicated that at the 50 and 100 prey densities, additive effects were occurred on the mortality of prey when two predators were used synchronously. Whereas predation in the combined uses of O. niger and A. intermedius at the 10 prey density, were not higher than the separated uses of each predator alone. Interaguild predation of O. niger, female and nymph V, on A. intermedius, adults and larvae-II, were observed also at the 10 prey density. The combined uses of O. niger and A. intermedius at high population density of onion thrips compare to low density can be successful in biological control of this pest.

Key Words: Interaction; Aeolothrips intermedius; Orius niger; Thrips tabaci; Predation; Potato

INTRODUCTION Adults and larvae I-II of A. intermedius were found as predator of thrips species specially F. occidentalis and onion Onion thrips (Thrips tabaci Lindeman) is a major pest thrips (Bournier et al., 1978 & 79; Lacasa et al., 1982; of many crops, which transmit TSWV on damaged plants Torres-Vila et al., 1994; Riudavets, 1995). (Van Rijn et al., 1995; Theunissen & Schelling, 1997; Frequently, Orius species were used in combination Jones, 2005). Its genetic elasticity has enabled it to develop with the predatory mites in biological control of thrips resistance to almost every insecticide applied in the field (Gillespie & Quiring, 1992; Sanchez et al., 1997; Fejt & (Lewis, 1997). Therefore using resistant plants, sticky traps Jarosı´k, 2000; Shipp & Wang, 2003). The impact of these and natural enemies for control of thrips can be useful combinations on thrips biological control was narrow (Alimousavi et al., 2007; Ranamukhaarachchi & mainly, because Orius species not only prey on thrips but Wickramarachchi, 2007). also on predatory mites, that is intraguild predation. In the potato fields of Ardabil region, onion thrips is In this study, we tested the hypothesis that intraguild the most frequently found alongwith Aeolothrips predation and additive effect are present among O. niger, intermedius (Bagnall) and Orius niger (Wolff) as major one female and one nymph-V and A. intermedius, three predators of onion thrips and it is found that they feed on adults and three larvae-II, in the separated and combined larvae-I-II and adults of onion thrips on potato. Therefore O. uses for the biological control of the onion thrips at three niger and A. intermedius could be good candidates for densities. Also we assessed that A. intermedius subjects to biological control of onion thrips on potato. predation by O. niger at three densities of prey. These Specific studies on th